Gas turbine jet propulsion engine

ABSTRACT

The invention concerns a gas turbine jet propulsion engine having compressor means, main combustion equipment, turbine means and first nozzle means in flow series; variable area second nozzle means which receive compressed air from at least part of the compressor means via conduit means which bypass the main combustion equipment and turbine means; nozzle area adjustment means for varying the area of the second nozzle means; additional combustion equipment for burning fuel in the said conduit means; a fuel supply control unit for controlling the supply of the said fuel, measuring means for measuring the dynamic pressure in the conduit means upstream of the additional combustion equipment, and control means which are acted upon by said measuring means and which control the nozzle area adjustment means.

United States Patent 72] Inventor Christopher Linley Johnson Derby,England [21 Appl. No. 856,427 [22] Filed Sept. 9,1969 45 Patented Aug.31, 1971 [73] Assignee Rolls-Royce Limited Derbyshire, England [32]Priority Sept. 11, 1968 [3 3] Great Britain [31 43258/68 [54] GASTURBINE JET PROPULSION ENGINE 2 Claims, 1 Drawing Fig.

[52] US. Cl 611/224, 60/235, 60/242 [51] Int. Cl F02k 1/18, F02k 3/00[50] Field of Search 60/224, 226, 233, 235, 237, 239,242, 225

[5 6] References Cited UNITED STATES PATENTS 2,641,105 6/1953 Drake60/39.28X

2,738,644 3/1956 Alford 60/235 2,766,580 10/1956 Buerer 60/3928 X2,912,188 11/1959 Singelmann et al.... 60/226X 3,0l5,935 1/1962 Evans60/235 3,300,976 l/l967 Coplin 60/224 Primary Examiner-Al Lawrence SmithAttorney-Cushman, Darby and Cushman ABSTRACT: The invention concerns agas turbine jet propulsion engine having compressor means, maincombustion equipment, turbine means and first nozzle means in flowseries; variable area second nozzle means which receive compressed airfrom at least part of the compressor means via con- GAS TURBINE JETPROPULSION ENGINE This invention concerns a gas turbine jet propulsionengine.

According to the present invention, in its broadest aspect, there isprovided a gas turbine jet propulsion engine having conduit means inwhich are arranged in flow series combustion equipment and variable areanozzle means, a fuel supply control unit for controlling the supply offuel to the said combustion equipment, nozzle area adjustment means forvarying the area of the said nozzle means, measuring means for measuringthe dynamic pressure in the conduit means upstream of the saidcombustion equipment, and control means, which are acted upon by saidmeasuring means, for controlling the nozzle area adjustment means.

In its preferred form, the present invention provides a gas turbine jetpropulsion engine having compressor means, main combustion equipment,turbine means and first nozzle means in flow series; variable areasecond nozzle means which receive compressed air from at least part ofthe compressor means via conduit means which bypass the main combustionequipment and turbine means; nozzle area adjustment means for varyingthe area of the second nozzle means; additinal combustion equipment forburning fuel in the said conduit means; a fuel supply control unit forcontrolling the supply of the said fuel, measuring means for measuringthe dynamic pressure in the conduit means upstream of the additionalcombustion equipment, and control means which are acted upon by saidmeasuring means and which control the nozzle area adjustment means.

The said measuring means may also comprise means for measuring apressure functionally related to the dynamic pres- 7 sure at the secondnozzle means when fuel is supplied to the additional combustionequipment.

The control means may control the nozzle area adjustment means in such away as to maintain a substantially constant relationship between thesaid dynamic pressures in the conduit means and at the second nozzlemeans.

The control means may comprise a bellcrank lever mounted on a fulcrum,the two arms of the bellcrank lever being respectively subjected by saidmeasuring means to forces which tend to rotate the bellcrank lever inopposite angular senses about the fulcrum.

The bellcrank lever may control the output of a pump adapted to supplyhydraulic liquid to control the nozzle area adjustment means.

The invention is illustrated, merely by way of example, in theaccompanying drawing, which shows a gas turbine jet propulsion engineaccording to the present invention.

In the drawing, there is shown a gas turbine jet propulsion engine 1having an engine casing 2 within which there are mounted in flow seriesa low pressure compressor 3, a high pressure compressor 4, maincombustion equipment 5, a high pressure turbine 6 which drives the highpressure compressor 4 through a shaft 7, and a low pressure turbine 9which drives the low pressure compressor 3 through a shaft 10.

The air compressed by the low pressure compressor 3 passes into a plenumchamber 11 and part of this air passes therefrom via conduits l2, 13(which bypass the main combustion equipment 5 and turbines 6,9) )to twodiametrically spaced-apart progressively variable area front nozzles l4,15 respectively which are under the control of hydraulically operatednozzle area adjustment rams 18, the front nozzles l4. 15 being rotatableto vary the direction of the efflux therefrom, whereby to vector" thethrust. Combustion equipment which includes fuel injectors 16, 17, areprovided in conduits l2, 13 respectively to enable this thrust to beincreased when desired, e.g. when used to effect vertical takeoff.

The turbine exhaust gases pass via conduits 20, 21 to two diametricallyspaced-apart rear nozzles 22, 23 which are also rotatable to vary thedirection of the efflux therefrom.

The fuel injectors l6, 17 are supplied with fuel, via pipes 25, 26, froman annular manifold 27. The annular manifold 27 is supplied with fuelthrough a fuel duct 33 which extends to the high pressure side of avapor core centrifugal pump 34.

The pump 34 has a fuel inlet 35 the communication between which and theeye" of the pump is controlled by an inlet throttle 36. The inletthrottle 36 is constituted by a sleeve whose interior may receive fuelfrom the fuel inlet 35. The inlet throttle 36 is movable towards andaway from a valve seat 37 by a fuel control supply unit 38 which isresponsive (by means not shown) to at least one engine variable andwhich is controlled by the setting of a manually operable pilots lever39.

A piston 40, to which is connected a linkage 41, is movable in acylinder 42, the piston 40 having oppositely disposed pressure surfaces43, 44. The pressure surfaces 43 is open to supply of fluid at a highpressure, e.g. to the fuel supplied to the main combustion equipment 5by way of a duct 45. The pressure surface 44 is open to the pressure ina duct 46 which communicateswith the duct 45 by way of a restriction 46.

The linkage 41 is connected to a swash plate 47 of a swash plate pump 48so that movement of the piston 40 adjusts the inclination of the swashplate 47 and hence the output of the pump 48. The high and low pressuresides of the pump 48 are connected by pipes 49 to the rams 18 so thatthe inclination of the swash plate 47 controls the positions of the rams18 and so controls the areas of the front nozzles l4, 15.

The duct 46 communicates with a chamber 50 by way of a variablerestriction 51 whose size depends upon the axial position of a valve rod52, the chamber 50 being connected to a low pressure source. The valverod 52 is connected for axial movement to one arm '53 of a bellcranklever 53, 54. The valve rod 52 is provided with a gear 55 which mesheswith an engine driven gear 56. The valve rod 52 is then continuouslyrotated in operation so as to help to prevent it from sticking, wherebyit will move readily on any change in the forces acting on the bellcrank lever 53,54.

It will thus be appreciated that movement of the bellcrank lever 53,54will adjust the position ofthe valve rod 52 and will therefore adjustthe pressure in the duct 46 and hence the pressure acting on thepressure surface 44. This will cause appropriate adjustment in theposition of the piston 40 and hence of the areas of the front nozzlesl4, 15.

The bellcrank lever 53, 54, which is pivotally connected by a link tothe wall ofa housing 61, is movable about a fixed fulcrum constituted bya roller 62 mounted on a rod 59. The arms 53, 54 of the bellcrank leverare subjected to two forces which tend to rotate the bellcrank lever inopposite angular senses about the roller 62, these two forces beingtransmitted to the bell crank lever 53, 54 from diaphragms 63, 64.

The housing 61 contains chambers 65, 66, 67. The chambers 65, 66 areseparated from each other by the diaphragm 63, and the chambers 66, 67are separated from each other by the diaphragm 64. The chambers 65, 66communicate with each other by way of restriction 68.

The chamber communicates via a restriction 69 with a duct 70 which isopen to atmosphere.

The chamber 66 communicates with a duct 73, which is arranged to receivethe total pressure prevailing at a point 73 immediately upstream of theregion in which the fuel is burned at the fuel injectors 16, 17, themass flow through the point 73 being substantially the same as thatthrough the nozzles 14, 15.

Since fuel is supplied to the fuel injectors 16, 17 only at or near topspeed, the front nozzles 14, 15 will be choked at this time and thedynamic head thereat will therefore be a fixed fraction of the totalpressure. Accordingly, the pressure acting on the diaphragm 63 at thistime will be functionally related to the dynamic pressure at the fuelinjectors 16, 17 and thus will also be functionally related to thedynamic pressure at the front nozzles 14, 15.

The chamber 67 communicates with one end of a duct 74 whose opposite endis arranged concentrically about the duct 73 and receives the staticpressure at the point 73'.

The force on the diaphragm 64 is therefore representative of the dynamichead at the point 73', i.e. at a point upstream of the fuel injectors16, 17.

As will be appreciated if the ratio between the dynamic pressures at thefront nozzles 14, 15, and that at the point 73' varies from that whichbalances the bellcrank lever 53, 54, movement will occur of thebellcrank lever 53, 54 about its roller 62 and this will cause axialmovement of the valve rod 52. The pressure in the duct 46 and so on thesurface 44 will alter, with the result that the rams 18 will vary theareas of the front nozzles 14, 15. This will in turn vary the backpressure acting on the low pressure compressor 3 in such a way as totend to restore the bellcrank lever 53, 54 to its original position.

lCLAlM:

1. A gas turbine jet propulsion engine having compressor bustionequipment and turbine means; nozzle area adjustment means for varyingthe area of the second nozzle means; additional'combustion equipment forburning fuel in the said conduit means; a fuel supply control unit forcontrolling the supply of the said fuel, measuring means for measuringthe dynamic pressure in the conduit means upstream of he additionalcombustion equipment and for measuring a pressure functionally relatedto the dynamic pressure at the second nozzle means when fuel is suppliedto the additional combustion equipment, and control means which areacted upon by said measuring means and which control the nozzle areaadjustment means in such a way as to maintain a substantially constantrelationship between the said dynamic pressures in the conduit means andat the second nozzle means.

2. An engine as claimed in claim 1 in which the control means comprisesa bellcrank lever mounted on a fulcrum, the two arms of the bellcranklever being respectively subjected by said measuring means to forceswhich tend to rotate the bellcrank lever in opposite angular sensesabout.the fulcrum.

1. A gas turbine jet propulsion engine having compressor means, maincombustion equipment, turbine means and first nozzle means in flowseries; variable area second nozzle means which receive compressed airfrom at least part of the compressor means via conduit means whichbypass the main combustion equipment and turbine means; nozzle areaadjustment means for varying the area of the second nozzle means;additional combustion equipment for burning fuel in the said conduitmeans; a fuel supply control unit for controlling the supply of the saidfuel, measuring means for measuring the dynamic pressure in the conduitmeans upstream of he additional combustion equipment and for measuring apressure functionally related to the dynamic pressure at the secondnozzle means when fuel is supplied to the additional combustionequipment, and control means which are acted upon by said measuringmeans and which control the nozzle area adjustment means in such a wayas to maintain a substantially constant relationship between the saiddynamic pressures in the conduit means and at the second nozzle means.2. An engine as claimed in claim 1 in which the control means comprisesa bellcrank lever mounted on a fulcrum, the two arms of the bellcranklever being respectively subjected by said measuring means to forceswhich tend to rotate the bellcrank lever in opposite angular sensesabout the fulcrum.